Copper-nickel-titanium alloys



Patented Dec. '14, 1937 COPPER-NIOKEL-TITANIUM ALLOYS Norman B. Pilling,Westfleld, N. J., and Paul D.

v Merica, New York, N. Y., a

ssixnors to {The International Nickel Company, Inc., New York, N. Y., acorporation of Delaware No Drawing.

Original application October 1,

1931, Serial No. 566,311. Divided and this al plication November 16,1935, Serial No. 50,240

31 Claims.

This invention relates to improved coppernickel-titanium alloys of thesolid solution type.

Hitherto it has been proposed to utilize the metal titanium as adeoxidizing agent for alloy steels and the like in which the residualcontent of titanium contemplated was very small, usually less than .1percent. It has been further proposed to use titanium as a tougheningagent or grain refiner in which cases the alloy may have some 1 percentof titanium retained, although several disclosures specify ranges oftitanium for such purposes up to 10 percent. It is an object of thepresent invention to provide improved hardenable nickel alloys bycombining with a suitable alloy, referred to as the base alloy,quantities of titanium and titanium-like elements.

It is a further object of this invention to con- ,fer hardeningproperties upon particular base alloy compositions chosen to provideother desirable properties, whereby not only the hardness but theelastic strength and breaking strength of the base alloy is increasedwithout materially changing its other characteristic properties.

It is a still further object of this invention to' alloy a suitablehardening agent with a nickelbearing base material and subject theresulting alloy to a particular heat treatment to develop and controlincreased strength properties. These and other desirable advantages ofthe present invention will be set forth and described in theaccompanying specification, certain preferred compositions being givenby way of example only, for, since the underlying principles may beapplied to other specific compositions, it is not intended to be limitedto those herein shown except as such limitations are clearly imposed bythe appended claims.

The present invention comprehends a wide variety of base alloycompositions and three preferred hardening agents, as Will be describedmore in detail hereinafter. The preferred base alloy which isparticularly amenable tothe proposed treatment may be defined asnickel-bearing solid solutions having the face-centered cubic latticetype of crystalline structure. The claim for this broad definition ispredicated on experimental work with siX distinct alloy series of thistype in addition to the metal nickel, all of which behave substantiallysimilarly, and which behavior will be described more in detail below. Noexceptions to this definition have yet been encountered, although thedegree of hardening displayed by different combinations of base alloyand hardening agent, of course, vary somewhat in degree. In one suchseries, viz., iron-nickelchromium-titanium, the hardeningcharacteristics were displayed in alloys having ranges of nickel contentvarying from substantially 6 to 96 percent.

The preferred hardening agents comprehended within the spirit and scopeof this invention are titanium, aluminum, and zirconium, and it isapparent that the hardening characteristics herein disclosed may beproperties orfunctions of the boron and the titanium groups of theperiodic classification of the elements according to 'Mendeleeff. Ofthese hardening agents titanium has been found to be the more usefulfrom the standpoint of developing physical properties of engineeringvalue combined with practical working' qualities.

For the purposes of illustration, in order to more clearly set forth thenovel features of the present invention, the characteristics ofironnickel base alloys alloyed with titanium as a hardening agent willbe discussed. Nickel-iron alloys which include from about 25 percent tosubstantially 100 percent nickel in their composition are soft andrelatively unaffected in hardness by heat treatment. Titanium is solublein these alloys and, if completely dissolved therein, the resultingternary alloys retain substantially the original soft character. If asufficient amount of titanium be added, however, the resulting alloysare soft only when cooled rather rapidly from a high temperature; ifreheated to some lower temperature range, or allowed to cool ratherslowly through this range, a substantial rise in hardness occurs. Astill further increase in titanium content causes the alloys to becomeincreasingly hard, even when subjected to rapid cooling from hightemperatures, yet these alloys change somewhat in hardness with heattreatment. These characteristics in a series of iron- 1 nickel alloyscontaining 35 percent nickel and varying amounts of titanium are shownin the following table:

to this particular base is from substantially 1 percent, at which pointhardening begins, to about i percent, at which point the malleability ofthe alloys becomes impaired. The hardened alloys in common withiron-nickel alloys generally are characterized by their toughness,resistance to attack by non-oxidizing acids, ierro-magnetism and highelectrical resistivity. With an increase in the nickel content of thebase alloy, the desirable range of titanium, as just defined, remainssubstantially the same up to percent nickel content, but the capacityfor hardening displayed by the alloys under consideration, steadilydiminishes with increase in nickel content up to 99% with a range ofabout 150 to 225 Brinell hardness units. Within the range of 75 to 96percent nickel content, the minimum titanium content necessary todevelop hardening, increases from about 1 percent to somewhat more than4 percent, the amount being roughly proportional to the excess of nickelover 75 percent. Within this range the hardness differential developedby heat treatmentais from about 75 to substan tially Brinell units.

Titanium when added to'many other nickel alloys of the face centeredcubic lattice type previously noted, permits the formation of alloyshaving hardening characteristics similar to the iron-nickel-titaniumalloys described. Among these other base alloys may be mentioned:Ironnickel-copper; iron-nickel-chromium; iron-nickel manganese;nickel-copper; nickel-chromium, and nickel metal. The following tableshows several malleable alloys exemplifying this fact, the hardnessnumbers being expressed in Brinell units:

Number Brinell hardness...

Soft (i000 C. w. (1.). Number Hard (600C. temp.

In the case of aluminum, the content of this element necessary todevelop suitable hardening response varies from about 2.5 tosubstantially 6 percent, the latter percentage marking the approximateupper limit of .forgeability. A preferred range is from 5.0 to 5.5percent- .When titanium is used as an alloying element, the use ofcommercial ferro-titanium may introduce appreciable quantities ofaluminum and silicon into the metal, both of which elements will appearin the resulting alloy. This content of aluminum is not harmful and ithas now been found in fact that the use of even higher contents ofaluminum in combination with titanium as Number 8 9 1o 11 12 13 14 15 1s17 1s 19 20 35 23. 3 1s. 4 15. 3 35. 5 93 80 20 2o 74 51 65 5e 0e 57 1.29 12 3 12 1.1 64 76 10 7.9 11.3 14.5 5 1 8.0 2.3 2.5 2.5 "53' 1.6 3.03.0 "T

80ft (1000 0. water quench) 127 157 159 154 153 152 126 194 300 154 Hard(tempered GOO-700 The ranges of the several elements in addition totitanium, may be extended as follows: copper .590%, chromium 330%,nickel 2-99%, and iron 2-90%, the titanium being replaceable, under theconditions discussed more in detail hereinafter, by from .5-10% oftitanium-like metals such as aluminum and/or zirconium. These elementsmay be associated with each other in any desired amounts to givecompositions having certain specified characteristics.

The preferred range of titanium is substantially from 1 to' 4 percent.This range is determined approximately by the first appearance ofhardening and the substantial disappearance of hot malleability. When itis desired to retain good hot and cold working properties in order topermit shaping by forging, hot rolling, cold rolling, drawing, orplastic deformation generally, full advantage cannot be taken of themaximum titanium content. In such casesdt is preferable to employtitanium contents ranging from 2.2 to 3.2 percent for alloys having alow carbon content and in which the base is nickel-iron,nickelcopper-iron, and nickel-chromium-iron. It will, of course, beunderstood that in case of castings where workability is not a factor tobe considered, a much greater range of titanium is permitted with acorrespondingly greater degree of hardening agents offers certainadvantages, notably in accelerating the rate at which the hardeningreaction occurs. As an example of this discovery, thenickel-iron-titanium alloy including 34.8 percent nickel, 2.2 percenttitanium, and 0.3 percent aluminum, showed no appreciable hardening whenair-cooled from 1000 degrees centigrade. A similar alloy including 34percent nickel, 2.5 percent titanium, and 1.9 percent aluminum increasedin hardness about 110 Brinell units on air-cooling. Both alloys hardenedto about 320 Brinell units when furnace cooled. Y It will also beappreciated that by the use of hardening agents in multiple as hereindescribed, it is possible to secure marked economies in manufacture dueto the ability to use cheaper addition materials without in any waysacrificing the good results desired in the finished product.

The diversity of base compositions amenable to hardening by titanium andaluminum has been described. No common alloying elements in amounts lessthan 2 percent have been found to interfere with this hardeningcharacteristic with the exception of aluminum and carbon. The effect ofaluminum when combined with titanium has just been described. Sincecarbon forms an inert titanium carbide, its presence with titanium ishighly detrimental. This is due to the fact that although the totaltitanium content may be great enough to indicate vigorous hardening, thealloy is, in fact, devoid of hardening response. It is highly-desirable,therefore, to keep the carbon content as low as is metallurgicallyfeasible. Alloys of this type have been produced with as little as .01percent carbon, yet melts containing as much as 0.40 percent carbon havebeen produced which displayed good hardening properties. although aninefliciently high titanium content in the alloy was necessary.

It is considered to be within the scope of this invention to provide, inaddition to the major elements of composition, such other elements asare commonly used in metallurgy to aid in refining, purifying,degasifying, and otherwise treating the alloy to insure its productionin sound, tough, malleable form. These auxiliary elements are:

Percent Manganese up to 5 Silicon up to 5 Aluminum up to 1 Vanadium upto 1 Zirconium up to 1 Titanium up to Calcium up to Magnesium up toBoron up to /2 The nature and quantity of these accessory elements isdetermined by the nature of the base alloy in question.

Many characteristics of the hardening action developed by titanium andits equivalents, as described hereinbefore suggest that it is of theso-called precipitation type, and that nickel, in association withtitanium and/or aluminum, is withdrawn from solid solution concurrentlywith the rise in hardness on heat treatment. Of course, this is only apossible theory and it is to be understood that we are not bound to thistheory.

To bring the alloys under consideration into the softest workingcondition, the heat treament required in all cases is a not too slowcooling from above a minimum temperature. Most efficient results areobtained when this minimum temperature is exceeded, but the temperaturemargin by which it is exceeded is not of very great im portance, theupper limit usually being that at which an undesirable coarsening ingrain size occurs. The minimum softening temperature varies directlywith increase in content of the hardening element or elements, and alsovaries to some extent with the composition of the base alloy. Forcontents of titanium and/oraluminum which yield malleable alloys, thisminimum temperature is generally from 750 degrees centigrade to 850 deg.centigrade, and can easily be established for a particular alloy. As ageneral rule the entire group of alloys herein described respond well toa range of softening temperatures varying from 900 deg. C.-to 1050 deg.C. The rate of cooling required to avoid hardening is not great, and aircooling will usually prove fast enough, although cooling in water or inoil is permissible.

Where it is desired .to heat treat the alloys in order to harden them,the treatment is much more variable. Variations in composition of thebase metal, and. of the hardening elements affect both the temperatureat which the desired hardening is most effectively produced, and alsothe rate at which it occurs. In all cases hardening occurs over aconsiderable range of temperatures, and the lower the temperature atwhich this can be carried out, the greater will be the hardnessultimately developed. Since the rate of hardening diminishes as thetemperature is decreased, an optimum hardening temperature may beappropriately designated.

With'a hardening treatment which includes holding the alloy at a fixedtemperature for several hours, the preferred hardening temperature issubstantially 700 deg. C. for alloys in which titanium is the hardeningelement, and about 600 deg. C. when aluminum or zirconium is thehardening element. It is to be noted that when chromium does not exceedabout 5 percent, good hardening may be produced by furnace cooling fromthe softening range; When the chromium content exceeds this value, thehardening reaction proceeds sluggishly, and considerably more time isrequired in order to develop full hardness. High chromium alloyscontaining up to 30% chromium may show very little hardening on furnacecooling.

When, it is desired to develop the maximum hardness of agiven alloy, ithas been found advantageous to carry out the hardening operations in.several steps at progressively lower temperatures and preferably withthe duration of heating increasingat the lower temperatures. Thetemperature range in which this incremental hardening may be carried outis from the minimum softening temperature above described,

down to about 500 deg. C. As a particular example, an alloy of acomposition including having an initial Brinell hardness of 148 hardenedto 290 Brinell after twenty-four hours of treatment at 700 deg. C. Whenan incremental hardening heat treatment'was given to this alloy, ahardness of 340 Brinell units was secured, the particular treatmentincluded heating at 750 C. for two hours, followed by heat treatment at600 deg. C. for five hours, and at 600 deg. C. for twenty-three hours.

On the other hand, for the purpose of improving toughness and ductilityof the hardened alby, the termination of the hardening operation mayinclude the step of reheating to a temperature higher than the lastpreceding step, but still within the range of temperature in which theparticular alloy is hardenable.

A further example may be given in which the hardening characteristics asdescribed hereinabove are combined with martensitic hardening of thetype commonly observed in air-hardening steels. This combination occursin marginal austenitic nickel-content ferrous alloys of the nickel,nickel-chromium, nickel-copper, nickelmanganese and related series inwhich the iron content is up to about 10 percent lower than that atwhich martensite ceases to be a constituent under ordinary conditions ofcooling.

Alloys of the aforesaid type when heat treated develop a strengtheningprecipitate, accompanied by a change in composition of the residualmatrix sufiicient to shift the latter within the range of compositionswhich have a true allotropic transformation, and hence, at suitablecooling velocities, can be transformed at least partially intomartensite. The following are two examples of alloys in which the effectis characterized by intense hardening.

These alloys were both completely austenitic and non-magnetic when inthe soft condition, but became magnetic and partially martensitic afterheating between 600 and 700 followed by cooling in the air.

As exemplifying the physical properties produced in malleable alloys ofthe type under consideration, the following table is included:

This adJustment generally involves a small increase in nickel content.

It will now be appreciated that there has been provided an improvedprocess for producing high strength alloys of the solid solution typecontaining nickel, which are initially soft and workable, which processcomprehends the use of suitable amounts of hardening agents such astitanium, aluminum and/or zirconium. It is to be noted further that thehardenable alloys comprehended within the spirit and scope of thepresent invention, are adapted for a wide variety of uses, and moreparticularly for use in structures which can economically be made byplastic deformation such as drawing, pressing, etc., such formedarticles being adapted to being suitably hardened by a heat treatment asset forth. Furthermore, the present invention has been described inconjunction with various compositions the nickel content op. Ult. Elong.Red at Izod F Tem limit strength 2" per- No. Ni Cu Cr Ti 0 per Psi Psicont percent mm sort.-. 24. 000 .500 31. 5 05. 1

25 $0 15 "{Hard 110,000 192,000 10.0 33.0

21 15.5 12.4 2.7 .00. Hatdmfifi 66,000 130,000 36 7; Hard 5)..-- 80,000160, 000 22 1s 50 (t)Ineremen temper.

In addition to exhibiting these high physical properties at roomtemperatures, the high strength and elastic properties shown may beretained at high temperatures, provided that, the base alloy is of asuitable type; iron-nickel-chromium is appropriate, and the titaniumalloy with this base shows excellent strength properties at temperaturesup to the hardening temperature. The steel designated as number 27in theabove table shows the following characteristics when broken in tensionat 600 deg. C. after previous full hardening:

90,000 psi PL. 125,000 psi Ult.

25% elong. in 2" 12% red.,area

Such alloys are particularly suited for purposes involving considerableheat and load such as obtained in steam and internal combustionturbines,

as well as in many chemical processes, a particular example being thatof tube stills and like apparatus which may be used in oil-cracking andoil refining.

Many alloys, in particular steels, exist which have hardness andtensile'properties equal to or even excelling the alloys of the presenttype. The advantage of the latter lies in the unique fact that thepresent hardening elements may add hardening properties to particularbase alloys without detriment to their other distinctive properties,thus ailfording a combination of strength with other special qualitiesnot previously possible. For example, the addition of titanium toausteriitic nickel-chromium steels imparts hardness and high elasticproperties without interfering with the valuable corrosion and heatresisting qualities of the latter. In particular cases in which aproperty is closely associated with a specific nickel content, e. g.,low expansivity in nickel-iron alloys, a slight adjustment ofcomposition may be necessary in the hardened alloy.

of which may be applied to any of alloys disclosed herein. Thus,specific nickel alloys containing about 6% and about 15% referred to onpages 1 and 4, respectively, but these nickel contents or variationsthereof within the scope of the present invention may be used in any ofthe present alloys. For example, a nickel alloy containing about 10%nickel, about 87% copper and about 3% titanium when in a soft conditionresulting from quenching in water from 900 C. had a Brinell hardnessnumber of 130 and when in a hard condition resulting from reheating to atemperature of about 600 C. t; abgut 700 C. had a Brinell hardnessnumber 0 8 This is a divisional application of Serial Number 566,311filed October 1, 1931, Patent 2,048,166, and continuation in partapplication of our application, Serial No. 356,870, filed April 15,1929, Patent 2,048,163.

What is claimed is:

1. A hard nickel-copper alloy containing about 2% to about 50% nickel,at least 1 to about 10% titanium, and copper constituting substantiallythe balance of the alloy, said alloy being age hardened by heating thealloy to an elevated temperature below its melting point butsufllciently high to cause titanium to go into solution, quenching thealloy and reheating to a temperature below that of the initial heatingbut sufliciently high and for a period of time sufficient to obtain asubstantial increasein the hardness of the alloy.

2. A hard nickel-copper alloy containing about 2% to about 50% nickel,at least 1 to about 4% titanium, and copper constituting substantiallythe balance of the alloy, said alloy being age hardened by heating thealloy to an elevated temperature below its melting point butsufiiciently high to cause titanium to go into solution, quenching thealloy and reheating to a temperature below that of the initial heatingbut willciently high and for a period of time sufiicient to obtain asubstantial increase in the hardness of the alloy.

3. A hard nickel-copper alloy containing about 2% to about 50% nickel,about 2.2% to about 3.2% titanium, and copper constituting substantiallythe balance 01' the alloy, said alloy being age hardened by heating thealloy to an elevated temperature below its melting point but sumcientlyhigh to cause titanium to go into solution, quenching the alloy andreheating to a temperature below that of the initial heating butsumciently high and for a period of time sumcient to obtain asubstantial increase in the hardness of the alloy.

4. A hard nickel-copper alloy containing about 2% to about 50% nickel,at least 1% to about 10% of titanium and copper constitutingsubstantially the balance of the alloy, said alloy being age hardened byheating for a suflicient period of time and at a sufllciently hightemperature between 750 C. and the melting point to dissolve at least aportion of the titanium 'in the alloy, cooling the alloy to atemperature below 750 C. and heating the alloy for a suflicient periodof time and at a sufllciently high temperature below 750 C. to obtain asubstantial increase in the hardness of the alloy.

' 5. A hard nickel-copper alloy containing about 2% to about 50% nickel,at least 1% to about 4% of titanium and copper constituting substan--tial1y the balance of the alloy, said alloy being age hardened byheating for a suflicient period of time and at a sufliciently hightemperature between 750 C. and the melting point to dissolve at least aportion of the titanium in the alloy, cooling the alloy to a temperaturebelow 750 C. and heating the alloy for a suiilcient period of time and'at a suiiiciently high temperature below 750 C. to obtain a substantialincrease in the hardness of the alloy.

6. A hard nickel-copper alloy containing about 2% to about 50% nickel,about 2.2% to about 3.2% of titanium and copper constitutingsubstantially the balance of the alloy, said alloy being age hardened byheating for a suflicient period of time and at a suiiiciently hightemperature between 750 C. and the melting point to dissolve at least aportion of the titanium in the alloy, cooling the alloy to a temperaturebelow 750 C. and heating the alloy for a sufllcient period of time andat a sufficiently high temperaturebelow 750 C. to obtain a substantialincrease in the hardness of the alloy.

7. A hard nickel-copper alloy containing about 10% titanium, and copperconstituting substantially the balance of the alloy, said alloy beingage hardened by heating for a suflicient period of time at asufliciently high temperature between 750 C. and the melting point ofthe alloy to cause at least a portion of the titanium to dissolve in thealloy, and cooling the alloy from the aforesaid temperature to about 500C. at a rate sufficiently slow to cause a substantial increase in thehardness of the alloy.

8. A hard nickel-copper alloy containing about 2% to about 50% nickel atleast 1% to about 4% titanium, and copper constituting substantiallythebalance of the alloy, said alloy being age hardened by heating for asufilcient period of time at a suillciently high temperature between 750C. and the melting point of the alloy to 2% to about 50% nickel, atleast 1% to about sufliciently slow to cause a substantial increase inthe hardness of the alloy.

9. A hard nickel-copper alloy containing about 2% to about 50% nickel,about 222% to about 3.2% titanium, and copper constituting substantiallythe balance of the alloy, said alloy being age hardened by heating for asufficient period of time at a suil'iciently high temperaturebetween 750C. and the melting point of the alloy to cause at least a portion of thetitanium to dissolve in the alloy, and cooling the alloy from theaforesaid temperature to about 500 C. at a rate sufllciently slow tocause a substantial increase in the hardness of the alloy.

10. A hard nickel-copper alloy containing about 20% to about 50% nickel,at least 1 to about 10% titanium, and copper constituting substantiallythe balance of the alloy, said alloy being age hardened by heatingthealloy to an elevated temperature below its melting point butsufliciently high to cause titanium to go into solution, quenching thealloy and reheating to a temperature below that of the initial heatingbut sufilciently high and for a period of time sufficient to obtain asubstantial increase in the hardness of the alloy.

11. A hard nickel-copper alloy containing about 20% to about 50% nickel,at least 1 to about 4% titanium, and copper constituting substantiallythe balance of the alloy, said alloy being age hardened by heating thealloy to an elevated temperature below its melting point butsufiiciently high to cause titanium to go into solution, quenching thealloy and reheating to a temperature below that of the initial heatingbut sufficiently high and for a period of time sufl'icient to obtain asub-- stantial increase in'the hardness of the alloy.

12. A hard nickel-copper alloy containing about 20% to about 50% nickel,about 2.2% to about 3.2% titanium, and copper constituting substantiallythe balance of the alloy, said alloy being age hardened by heating thealloy to an elevated temperature below its melting point butsufficiently high to cause titanium to go into solution, quenching thealloy and reheating to a temperature below that of the initial heatingbut suificiently high and for a period of time suflicient to obtain asubstantial increase in the hardness of the alloy.

13. A hard nickel-copper alloy containing about 20% to about 50% nickel,at least 1% to about 10% of titanium and copper constitutingsubstantially the balance of the alloy, said alloy being age hardened byheating for a sufiicient period of time and at a, sufiiciently hightemperature between 750 C. and the melting point to dissolve' time andat a sufliciently high temperature below 750 C. to obtain a substantialincrease in'the hardness of the alloy.

14. A hard nickel-copper alloy containing about 20% to about 50% nickel,at least 1% to about 4% of titanium and copper constitutingsubstantially the balance of the alloy, said alloy being age hardened byheating for a sufiicient period of time and at a sufficiently hightemperature between 750 C. and the melting point to dissolve at least aportion of the titanium in the alloy, cooling the alloy to a temperaturebelow 750 C. and heating the alloy for a suflicient period of time andat a sufliciently high temperature below 750 C. to obtain a substantialincrease in the hardness of the alloy.

15. A hard nickel-copper alloy containing about 20% to about nickel,about 2.2% to about 3.2% of titanium and copper constitutingsubstantially the balance of the alloy, said alloy being age hardened byheating for a suilicient period of time and at a suiliciently hightemperature between 750 C. and the melting point to dissolve at least aportion of the titanium in the alloy, cooling the alloy to a temperaturebelow 750 C. and heating the alloy for a sufiicient .period of time andat a sufllciently high temperature below 750 C. to obtain a substantialincrease in the hardness of the alloy.

16. A hard nickel-copper alloy containing about 20% to about 50% nickel,at least 1% to about 10% titanium, and copper constituting substantiallythe balance of the alloy, said alloy being age hardened by heating for asuillcient period of time at a suiiiciently high temperature between 750C. and the melting point of the alloy to cause at least a portion of thetitanium to dissolve in the alloy, and cooling the alloy from theaforesaid temperature to about 500 C. at a rate sufliciently slow tocause a substantial increase in the hardness of the alloy.

17. A hard nickel-copper alloy containing about 20% to about 50% nickel,at least 1% to about 4% titanium, and copper constituting substantiallythe balance of the alloy, said alloy being age hardened by heating for asuillcient period of time at a sufllciently high temperature between 750C. and the melting point of the alloy to cause at least a portion of thetitanium to dissolve in the alloy, and cooling the alloy from theaforesaid temperature to about 500 C. at a rate sufllciently slow tocause a substantial increase in the hardness of the alloy.

18. A hard nickel-copper alloy containing about 20% to about 50% nickel,about 2.2% to about 3.2% titanium, and copper constituting substantiallythe balance of the alloy, said alloy being age hardened by heating for asumcient period of time at a sufliciently high temperature between 750C. and the melting point of the alloy to cause at least a portion of thetitanium to dissolve in the alloy, and cooling the alloy from theaforesaid temperature to about 500 C. at a rate sufficiently slow tocause a substantial increase in the hardness of the alloy.

19. A hard nickel-copper alloy containing about 10% to about 50% nickel,at least 1 to about 10% titanium, and copper constituting substantiallythe balance of the alloy, said alloy being age hardened by heating thealloy to an elevated temperature below its melting point butsufliciently high to cause titanium to -go into solution, quenching thealloy and reheating to a temperature below that of the initial heatingbut sumciently high and for a period of time suflicient to obtain asubstantial increase in the hardness of the alloy.

20. A hard nickel-copper alloy containing about 10% to about 50% nickel,at least 1% to about 10% of titanium and copper constitutingsubstantially the balance of the alloy, said alloy being age hardened byheating for a suflicient period of time. and at a sufliciently hightemperature between 750 C. and the melting point to dissolve at least aportion of the titanium in the alloy, cooling the alloy to a temperaturebelow 750 C. and heating the alloy for a sufllcient period of time andat a suiilciently high temperature below 750 C. to obtain a substantialincrease in the hardness of the alloy.

21. A hard nickel-copper alloy containing about 10% to about 50% nickel,at least 1% to about 10% titanium, and copper constituting substantiallythe balance of the alloy, said alloy being age hardened by heating for asufljlcient period of time at a suillciently high temperature between750 C. and the melting point of the alloy to cause at least a portion ofthe titanium to dissolve in the, alloy, and cooling the alloy from theaforesaid temperature to about 500C. at a rate suillciently slow tocause a substantial increase in the hardness of the alloy.

22. A hard nickel-copper alloy containing about 10% to about 50% nickel,at least 1 to about 4% titanium, and copper constituting substantiallythe balance of the alloy, said alloy being age hardened by heating thealloy to an elevated temperature below its melting point butsuiiiciently high to cause titanium to go into solution, quenching thealloy and reheating to a temperature below that of the initial heatingbut sumciently high and for a period of time suflicient to obtain asubstantial increase in the hardness of the alloy.

23. A hard nickel-copper alloy containing about 10% to about 50% nickel,at least 1% to about 4% of titanium and copper constitutingsubstantially the balance of the alloy, said alloy being age hardened byheating for a sumclent period of time and at a sufllciently hightemperature between 750 C. and the melting point to dissolve at least aportion of the titanium in the alloy, cooling the alloy to a temperatureincrease in the hardness of the -alloy.-

24. A hard nickel-copper alloy containing about 10% to about 50% nickel,at least 1% to about 4% titanium, and copper'constituting substantiallythe balance of the alloy, said alloy being age hardened by heating for asuilicient period of time at a sufllciently high temperature between 750C. and the melting point of the alloy to cause at least a portion of thetitanium to dissolve in the alloy, and cooling the alloy from theaforesaid temperature to about 500 C. at a rate sufliciently slow tocause a substantial increase in the hardness of the alloy.

25. A process for improving copper alloys including .1 to 4 per centtitanium which comprises quenching the said alloys at temperatures ofabout 650 to 1000 C. and then aging at about 250 to 600 C.

26. A process for improving copper-titanium alloys including apredominating amount of copper and some titanium which comprises coolingsaid alloys from temperatures of about 650 to 1000 C. and then agingthem at about 250 to 600 C.

27. The process for treating an alloy consisting substantially of copperand titanium, the titanium being present in the alloy in but minorquantity, said process comprising heating said alloy to a temperaturebetween about 650 C. to 1000 C., quickly cooling the alloy, and thenreheating it to a temperature between about 250 C. to 600 C. g

28. The process of treating an alloy consisti substantially of copperand titanium, the titanium being present in but minor quantities, saidprocess comprising heating said alloy to a relatively high temperature,quenching the alloy,

and then reheating it to a relatively low temperature to age-harden thealloy.

29. Heat-hardened copper-titanium alloys conamazes to temperaturesranging from about 650 to 1000" C., followed by aging at temperatures offrom about 250 to 600 C.

30. Heat-hardened copper-titanium alloys containing titanium inquantities ranging from a small but detectable amount up to about 4 percent by weight and also containing up to 10 per cent of additionalhardening metals selected from a group consisting of nickel, chromium,manganese, iron, cobalt and molybdenum; said alloys having the tensilestrength, electrical resistance and other properties produced by a heattreatment comprising heating said alloy to temperatures ranging fromabout 650 to 1000 C., followed by aging at temperatures of from about250 to 600 C.

31. The process of treating an alloy containing titanium in quantitiesranging from a small but detectable amount up to about 4 per cent byweight and also containing up to 10 per cent of additional hardeningmetals selected from a group consisting of nickel, chromium, manganese,iron, cobalt and molybdenum, said process comprising heating said alloyto temperatures ranging from about 650 to 1000 0., followed by aging attemperatures of from about 250 to 600 C.

NORMAN B. PILLING. PAUL D. MERICA.

